Describe a main goal of secondary treatment in a modern sewage treatment plant.

Explanation:

The main goal of secondary treatment is the further treatment of the liquid waste from primary treatment to remove the residual organics and suspended solids. Most times, secondary treatment follows primary treatment and involves the removal of biodegradable dissolved and colloidal organic matter using aerobic biological treatment processes. Aerobic biological treatment as the name implies, it is performed in the presence of oxygen by aerobic microorganisms (principally bacteria) that metabolize the organic matter in the wastewater, thereby producing more microorganisms and inorganic end-products majorly CO2, NH3, and H2O.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

you need to have a picture of the atom that way we can answer it